A variety of different industries use extractors to extract and recover liquid substances entrained within solids. For example, producers of oil from renewable organic sources use extractors to extract oil from oleaginous matter, such as soybeans, rapeseed, sunflower seed, peanuts, cottonseed, palm kernels, and corn germ. The oleaginous matter is contacted with an organic solvent within the extractor, causing the oil to be extracted from a surrounding cellular structure into the organic solvent. As another example, extractors are used to recover asphalt from shingles and other petroleum-based waste materials. Typically, the petroleum-based material is ground into small particles and then passed through an extractor to extract the asphalt from the solid material into a surrounding organic solvent.
Regardless of the application in which an extractor is used, manufacturers and operators of extractors are continuously looking for ways to improve the economic efficiency of their extractor operation. This can involve controlling the extractor to maximize the amount of extract recovered from a given feedstock while minimizing the amount of solvent lost during extraction and recovery. This can also involve operating the extractor harder by increasing the feedstock flow rate through the extractor. Unfortunately, attempts to increase feedstock flow rate through an extractor often result in a corresponding decrease in extract recovery. This can occur when the feedstock does not have sufficient residence time within the extractor and/or the increased feedstock volume inhibits proper intermixing between the extraction solvent and the feedstock.